Evening all, I currently have a house that has been valued at £350k. I have a mortgage currently that has 18 years left to run and have £247k worth of equity. What could I borrow, the online calculators aren't really conclusive.

I currently earn £38k but am getting a pay rise in January but would like to not factor this in as that'll be my mortgage over payment and holiday money. I'm 35 and would really like to take the next step up in terms of house ideally £370-400k house.